Authors Support in the TM4L Environment

The TM4L environment enables the development and use of ontology-aware courseware based on the Semantic Web technology Topic Maps. In this paper we discuss its features in the light of authoring support, giving illustrative examples to highlight its use

TwinPCG: Dual Thread Redundancy with Forward Recovery for Preconditioned Conjugate Gradient Methods

Even though iterative solvers like the Preconditioned Conjugate Gradient method (PCG) have been studied for over fifty years, fault tolerance for such solvers has seen much attention in recent years. For iterative solvers, two major reliable strategies of recovery exist: checkpoint-restart for backward recovery, or some type of redundancy technique for forward recovery. Efficient low-overhead redundancy techniques like algorithm-based fault tolerance for sparse matrix-vector products (SpMxV) have recently been proposed. These techniques add resilience with a good, but limited scope; state-of-the-art techniques correct at most 1 fault within a SpMxV. In this work, we study a more powerful resilience concept, which is redundant multithreading. It offers more generic and stronger recovery guarantees, including any soft faults in PCG iterations (among others covering SpMxV), but also requires more resources. We carefully study this redundancy-efficiency conflict. We propose a fault-tolerant PCG method, called TwinPCG, which introduces very small wall-clock time overhead, and significant advantages in detection and correction strategies. Our method uses Dual Modular Redundancy instead of the more expensive Triple Modular Redundancy (TMR); still, it retains the TMR advantages of fault correction. We describe, implement, and benchmark our iterative solver, and compare it in terms of efficiency and fault tolerance capabilities to state-of-the-art techniques. We find that before multithreading in BLAS, TwinPCG introduces 5-6% runtime overhead compared to reference PCG implementations, and can exploit BLAS multithreading well. In the presence of faults, it reliably performs forward recovery for a range of problems, showing all the strengths of TMR techniques

On the Balance Sheet-Based Model of Financial Reporting

The FASB adopted a balance sheet-based model of financial reporting about 30 years ago, and this model has been gradually expanded and solidified to become the required norm around the world today. Currently, the FASB and the IASB are re-considering their Conceptual Framework, and this is the right time to have a much-needed debate about the proper conceptual foundations of accounting. This paper argues that the balance sheet orientation of accounting standard-setting is flawed, for the following reasons: 1. Accounting is supposed to reflect business reality, and thus the essential features of the financial reporting model need to reflect the essential features of the underlying business model. However, the balance sheet orientation of financial reporting is at odds with the economic process of advancing expenses to earn revenues, which governs how most businesses create value, and which represents how managers and investors view most firms. 2. The adoption of the balance sheet approach was driven by conceptual considerations; standard setters argued that the concept of assets is more fundamental and logically prior to the concept of income. However, this paper argues that the concept of income is clearer and practically more useful than the concept of assets, especially with the recent proliferation of intangible assets. 3. Earnings is the single most important output of the accounting system. Thus, intuitively, improved financial reporting should lead to improved usefulness of earnings. However, the continual expansion of the balance sheet approach is gradually destroying the forward-looking usefulness of earnings, mainly through the effect of various asset re-valuations, which manifest as noise in the process of generating normal operating earnings. During the last 40 years, the volatility of reported earnings has doubled and the persistence of earnings has gone down by about a third, while there is little change in the properties of the underlying business fundamentals. 4. The balance sheet approach has pushed accounting into incorporating more and more valuation estimates into financial reports, creating tautological and dangerous feedback loops between financial markets and the real economy. The paper concludes with two suggestions about a "good" model of financial reporting. The first suggestion is that accounting needs to make a sharp theoretical and practical distinction between operating and financing-type activities and assets, and this distinction needs to be reflected in all financial statements. The second suggestion is that for most firms the accounting for operating activities needs a renewed emphasis on the principle of matching of expenses to revenues

A Digital Repository Supporting Collaboration

Today’s digital learning repositories are focused on the process of sharing materials created elsewhere. We propose a new type of digital learning repository which is focused on on-line collaboration. This new type of repository will foster an active community which creates and shares resources. It will use a mix of existing and new technologies to encourage users to communicate, contribute, and collaborate. It will be focused on the needs of instructors and be tolerant of differences of opinion

A fresh look at introductory data science

The proliferation of vast quantities of available datasets that are large and complex in nature has challenged universities to keep up with the demand for graduates trained in both the statistical and the computational set of skills required to effectively plan, acquire, manage, analyze, and communicate the findings of such data. To keep up with this demand, attracting students early on to data science as well as providing them a solid foray into the field becomes increasingly important. We present a case study of an introductory undergraduate course in data science that is designed to address these needs. Offered at Duke University, this course has no pre-requisites and serves a wide audience of aspiring statistics and data science majors as well as humanities, social sciences, and natural sciences students. We discuss the unique set of challenges posed by offering such a course and in light of these challenges, we present a detailed discussion into the pedagogical design elements, content, structure, computational infrastructure, and the assessment methodology of the course. We also offer a repository containing all teaching materials that are open-source, along with supplemental materials and the R code for reproducing the figures found in the paper

Study into the process of defective railtrack arc-hardfacing

The paper focuses exclusively on the manual arc hardfaced layers of railtrack repairing. The study is conducted in two stages- structural analysis of layers and mechanical characteristic(hardness) study. Two types of technologies for defective areas rebuilding are developed. The first one is hardfacing without a buffer layer, and the second one is with a buffer layer. The process is carried out using electrodes particularly appropriate for this purpose, namely OK 83.28 and OK 67.45, and is designed to achieve the original hardness of the railtrack. All in all, the desired hardness value and magnitude can be achieved by hardfacing the defective areas without a buffer layer, and with the use of OK 63.28 electrodes

Survey on Patients' Perceptions of Satisfaction with Rehabilitation Programs in a Diagnostic-Consultative Center

Medical rehabilitation is a complex process, as a result of which patients develop an active attitude towards their impaired health and restore a positive attitude to life, family, and society. It allows expanding the range of therapeutic effects in the early stages of the disease to prevent recurrence and progression. It supports social and labor adaptation and helps to ensure the independent existence of an individual in society.This article aims to examine the opinions of patients about the proposed rehabilitation programs at St. Marina University Hospital, Varna.The results obtained show good awareness of the therapeutic impact of rehabilitation procedures. Patients are increasingly seeking and using physical therapy, and it is the preferred method of treatment. There is a high level of satisfaction with the offered rehabilitation programs at St. Marina University Hospital, Varna

Connecting and Sharing Open-Content Learning Resources

While the number of learning repositories is increasing, there is no sufficient understanding of how to motivate and facilitate educators to share and reuse learning content. This paper proposes a framework addressing these challenges by integrating traditional approaches with Web 2.0 and Semantic Web technologies. It illustrates how the proposed approaches are used to implement LinkedCourse, a prototype repository for rapid collaborative development, sharing, and reuse of resources for emerging disciplines. The focus of the paper is on the collaborative annotation and community formation supporting the social framework of LinkedCourse

MPI Support on the Grid

Grids as infrastructures offer access to computing, storage and other resources in a transparent way. The user does not have to be aware where and how the job is being executed. Grid clusters in particular are an interesting target for running computation-intensive calculations. Running MPI-parallel applications on such clusters is a logical approach that is of interest to both computer scientists and to engineers. This paper gives an overview of the issues connected to running MPI applications on a heterogenous Grid consisting of different clusters located at different sites within the Int.EU.Grid project. The role of a workload management system (WMS) for such a scenario, as well as important modifications that need to be made to a WMS oriented towards sequential batch jobs for better support of MPI applications and tools are discussed. In order to facilitate the adoption of MPI-parallel applications on heterogeneous Grids, the application developer should be made aware of performance problems, as well as MPI-standard issues within its code. Therefore tools for these issues are also supported within Int.EU.Grid. Also, the special case of running MPI applications on different clusters simultaneously as a more Grid-oriented computational approach is described